The present invention relates to sealing boots, and more particularly to a sealing boot of elastomeric material for use to arrange a seal at a sliding portion in an hydraulically operated disc brake assembly, a sliding portion in a piston and wheel cylinder assembly or the like in order to prevent entry of foreign matter such as water, dirt and mud into an annular opening at the sliding portion.
Such a sealing boot as described above is an integral one-piece moulding of synthetic rubber or rubber like material which is arranged to hermetically enclose an annular opening between support and movable members in relatively reciprocable relationship. The sealing boot includes a tubular bellows which is integrally formed at the opposite ends thereof with a pair of cylindrical sealing sleeve portions respectively attached to the support and movable members. In such a construction, one of the cylindrical sealing sleeve portions is integrally connected substantially at its center to one end of the tubular bellows to effect a reliable sealing ability during expansion and contraction of the bellows in relative movements of the support and movable members. For example, in a conventional sealing boot as shown in FIG. 4, a cylindrical sealing sleeve portion 2 of generally rectangular cross-section is integrally connected substantially at its center with one end 1a of a tubular bellows portion 1. During the moulding process of such a sealing boot, the sealing sleeve portion 2 on a moulding die 3 is arranged to be removed by the air under pressure from an arrow direction A. It has, however, been experienced that the sealing sleeve portion 2 may not be removed from the moulding die 3 because the air entering between the inner peripheral surface 2a of portion 2 and the corresponding surface of die 3 pushes up the sealing sleeve portion 2 to cause abutment at its inner end shoulder against the corresponding annular protrusion of die 3. This results in time consumption for removal of the sealing sleeve portion 2 from the die 3.